Transcript Folie 1 - Air Commodities
Meeting ASHRAE Fundamentals, Standard 55 & 62.1 with Chilled Beams Displacement Ventilation.
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ASHRAE Standard 62.1-2009
Space Ventilation for Non-residential Occupancies
Ventilation for Acceptable Indoor Air Quality
• Classifies occupied spaces • Sets ventilation requirements based on size and occupancy • Sets guidelines for demand control ventilation
ASHRAE Standard 62.1-2009
Space Ventilation for Non-residential Occupancies
Conventional Method • Ventilate the space according to ASHRAE 62-2009 • Use Ventilation Rate or IAQ Procedure to determine OA requirements using table 6-1 3
ASHRAE Standard 62.1-2009
Space Ventilation for Non-residential Occupancies
• Conventional Method Ventilate the space according to ASHRAE 62 2009 • Use Ventilation Rate or IAQ Procedure to determine OA requirements using table 6-1 • Make Corrections for Zone Air Distribution Effectiveness using Table 6-2 4
ASHRAE Standard 62.1-2009
Space Ventilation for Non-residential Occupancies
• Conventional Method Ventilate the space according to ASHRAE 62 2009 • Use Ventilation Rate or IAQ Procedure to determine OA requirements using table 6-1 • Make Corrections for Zone Air Distribution Effectiveness using Table 6-2 • Make Corrections for Multiple Zone Recirculating System using Table 6-3 Z p =V oz /V pz 5
ASHRAE Standard 62.1-2009
Space Ventilation for Non-residential Occupancies
• • • • Conventional Method Ventilate the space according to ASHRAE 62 2009 Use Ventilation Rate or IAQ Procedure to determine OA requirements using table 6-1 Make Corrections for Zone Air Distribution Effectiveness using Table 6-2 Make Corrections for Multiple-Zone Recirculating System using Table 6-3 Z p =V oz /V pz 6
ASHRAE Standard 62.1-2009
Space Ventilation for Non-residential Occupancies
Conventional Method Our Goal is to Reduce the Amount of Treated Air Traveling Through the Building • 62.1 Dynamic Reset a.k.a. CO2 Ventilation • How does the Outdoor Air know where to go?
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ASHRAE Standard 62.1-2009
Space Ventilation for Non-residential Occupancies
Goal: Reduce the Amount of Conditioned Air Traveling Through the Building -So how else can we reduce the treated air???
Chilled Water Displacement (above the dew point)
Free Cooling Hours for 54F & 69F
18“ x 18“ Air Duct
3000 2500 2000 1500 1000 500 0
54F 69F 1“ diameter Water Pipe
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ASHRAE Standard 62.1-2009
Space Ventilation for Non-residential Occupancies
Goal: Reduce the Amount of Conditioned Air Traveling Through the Building -So how else can we reduce the treated air???
Displacement Chilled Water (above the dew point) 9 Displacement Terminal QLI Disp. Term w/ Coil Active Chilled Beam
ASHRAE Standard 62.1-2009
Space Ventilation for Non-residential Occupancies
Ideally get to a… DOAS • The system is simplified.
• Constant Volume • No return air.
One Step Further… DOAS w/ CO2 Sensor • The Fresh Outside Air goes where it’s need.
• More Complicated due to VAV 10
Implementing ASHRAE Standard 62.1
While Not Abusing ASHRAE Standard 55 & Fundamentals Near/Adjacent Zone High Airflow / Draft
No comfort zone 11
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ASHRAE Standard 55-2009
Thermal Comfort Guide
• Defines “Occupied Zone” • Factors affecting thermal comfort – Metabolic rate – Clothing (insulation) – Air temperature and speed – Radiant effects – Humidity • Defines acceptable conditions • Goal is occupant satisfaction levels 80% or higher
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ASHRAE Standard 55-2009
Occupied Zone
• Defines “Occupied Zone” Occupied zone definition – Not within two (2) feet of a wall – Between the floor and the head level of the predominant space occupants
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ASHRAE Standard 55-2009
Thermal Comfort Guide
• • Defines “Occupied Zone” Factors affecting thermal comfort – Metabolic rate – Clothing (insulation) – Air temperature and speed – Radiant effects – Humidity
Clothing
Radiant transfer to cooler surfaces Independent of air conditions Dependent on temperature of surfaces Dependent on orientation of surfaces
Occupant Thermal Comfort
Basic principles
SHG = Metabolic Rate
Convective transfer to surrounding air Dependent on air conditions Effected by air speed
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Thermal comfort achieved when heat out is equal to heat generated
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ASHRAE Standard 55-2009
Thermal Comfort Guide
• • • Defines “Occupied Zone” Factors affecting thermal comfort Defines acceptable conditions
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ASHRAE Standard 55-2009
Cooling Operation Comfort Range Assumes 1.0 Clo, 40% Tu and ≤ 40 FPM mean velocity
0.014
0.013
0.012
0.011
0.010
0.009
0.008
0.007
65 Cooling Operation Comfort Window 70 75 80
Operative Temperature, °F
85
60 57 55 50
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ASHRAE Standard 55-2009
Thermal Comfort Guide
• • • • Defines “Occupied Zone” Factors affecting thermal comfort Defines acceptable conditions Goal is occupant satisfaction levels 80% or higher
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ASHRAE Standard 55-2009 & Fundamentals
Lets Start with Displacement Ventilation
Return
Displacement Supply Air Thermal Plume Neck Level Near Zone Ankle Level
ASHRAE Standard 55-2009 & Fundamentals Near/Adjacent Zone
Adjacent zone is defined as the region adjacent to the terminal discharge in which terminal velocities exceeding 0.2 m/s (40 FPM) may be found that are 71F or below. It is indicated by the dimension L 0.2
as shown.
To avoid draft complaints, stationary space occupants should not be located within this region.
L 0.2
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Stratification Zone
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T S Near/Adjacent Zone Supply Layer ASHRAE Standard 55-2009 & Fundamentals T E Stagnation Layer Max. 5 o F T R
Occupied Zone
Ankle Level
T A
Comfort Chart – Ankle Region
ASHRAE Standard 55-2009 & Fundamentals T E Stagnation Layer Max. 5 o F T R Stratification Zone
Occupied Zone
Ankle Level
T A
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T S Supply Layer
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ASHRAE Standard 55-2009 & Fundamentals T E Stagnation Layer
Comfort Chart – Neck Region
Max. 5 o F T R Stratification Zone
Occupied Zone
Ankle Level
T A T S Supply Layer
Adjacent Zone Comparison (Face size of 24x48") Trox Titus Halton Price
370 cfm 300 cfm 225 cfm 24 150 cfm 0 2 4 6 8 10
Length (ft)
12 14 16 18
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Adjacent Zone Effect So why is there such a difference between manufacturers?
Nozzles VS Perforated
26 Tag DT-1 DT-2 DT-3 Include the Max. Allowable Adjacent Zone in the Schedule Model INC INC INC Displacement Terminal Schedule Size 24x48 24x48 24x48 CFM 225 150 300 Max Adjacent Zone @ 10F 6ft 5ft 8ft
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ASHRAE Standard 55-2009 & Fundamentals
Now Lets Look at Active Chilled Beams Ducted primary air Discharge to Room
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ASHRAE Standard 55-2009 & Fundamentals What is an Active Chilled Beam?
It‘s a Diffuser!
Room sees two slot linear diffusers, nothing more!
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ASHRAE Standard 55-2009
Now Lets Look at Active Chilled Beams • Defines “Occupied Zone” • Factors affecting thermal comfort – Metabolic rate – Clothing (insulation) – Air temperature and speed – Radiant effects – Humidity • Defines acceptable conditions • Goal is occupant satisfaction levels 80% or higher
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T 50 T 150 T 100 ASHRAE Standard 55-2009
Mixed Air Systems
T 100 T 150 T 50 OCCUPIED ZONE
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ASHRAE Fundamentals
Cooling Operation Comfort Range
Acceptable to 80%
Dissatisfaction Criteria
5% to 15% recommended limit
15%
for draft (mixed flow)
Part 1 – Chilled Beam
Active Chilled Beams
Mixed Room Air Distribution
Room Airflow
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The primary air via a diffuser (Beam)
•Provides fresh air requirement •Controls temperature •Controls humidity
Part 1 – Chilled Beam
Active Chilled Beams
Mixed Room Air Distribution
Room Airflow
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What does a diffuser do?
Delivers fast cold (or hot) air to the space It directs the discharge Makes use of the Coand ă effect Reduced velocity by mixing Changes temperature by mixing
Part 1 – Chilled Beam
Active Chilled Beams
Mixed Room Air Distribution
Room Airflow
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Beam vs. diffuser
Increases volume, Example: assume 60% water 40% air • 100 cfm by diffuser, 40 cfm @ beam but with induction ratio of say 4:1, = total air discharged is 40 x 4 + Original 40 = 200 cfm If we work on 1cfm/SF and room Height of 10’ 100 cfm = 6 ac/hr, 200 cfm = 12 ac/hr (room air movement) The increased discharge temperature helps but the higher volume throws further in a ‘more active space’.
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ASHRAE Standard 55-2009
36 4 or 2 pipe beam
Input Water Flow Rate (s) Input Primary air, Room and CWS Temperatures
Output: Sensible from Water, Air and Total Output Waterside, Airside Pressure drop and noise Output: Sensible from Water, Air & Total
37 Input Beam Length and Nozzle Type Input Primary Airflow Rate Input Beam Mounting Details for Local Velocity Predictions
Part 1 – Chilled Beam
Active Chilled Beams
Mixed Room Air Distribution
Room Airflow
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Beams must be selected for comfort, not just BTU’s
The selection programs will also show you that as you increase the cooling but maintain the cfm volume, the throw increases.
Beware of any proposition that half the number of beams for a given design when no throw data or statement on comfort is offered.
Active Chilled Beam Velocities
• ASHRAE and AHRI working to establish testing and rating standards – Sensible cooling capacities – Aerodynamic performance (throw data) – Acoustical performance • Many manufacturers do not catalog throw or velocity data • One proposes selections with discharge airflow rates > 100 CFM/LF – Results in T 100 values of 20 to 25 feet – Requires minimum diffuser separation of 50 to 60 feet for ADPI ≥ 80 39
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ASHRAE Fundamentals & Standard 55
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ASHRAE Fundamentals & Standard 55
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Thank You!
Designing Chilled Beam Systems for Thermal Comfort